1. Field of Invention
The present invention relates to a board-warping measuring apparatus. More particularly, the present invention relates to a board-warping measuring apparatus having a projection module for projecting a pattern onto a device under test.
2. Description of Related Art
In recent years, due to the reduction in the size of devices, many different types of automatic high-precision testing equipment have been developed for detecting the appearance of electronic components, wire connections, and whether alignment is correct. For example, automatic solder paste inspectors have been widely utilized in production lines to accurately measure the amount of solder pasted on substrates so as to serve as a necessary tool for process control in printed circuit board manufacturing.
In practical applications, printed circuit boards may be impacted by external stress or gravity to cause board warping. Board warping will result in a reduced accuracy when the device under test is measured by the measuring apparatus. For example, because of the deviation of the device under test in the vertical direction caused by warpage of the board, portions of the device under test which are intended to be measured are not within an optimal range of image-capturing focal length. Hence, the image thus captured is blurred.
A traditional board-warping measuring method is performed by employing a triangulation method, in which laser light is projected onto the device under test and a height of the device under test is calculated based on the reflected laser light. Next, a determination is made as to whether board warping of the device under test occurs. However, only the height of a small part of the device under test can be calculated by utilizing the laser light. In order to obtain the overall height of the device under test, the laser light needs to be projected onto every portion of the device under test in sequence. Such a process will lead to poor measurement efficiency, resulting in too much time being spent on the process.
For the forgoing reasons, there is a need to solve the above-mentioned problems by providing a board-warping measuring apparatus and a board-warping measuring method thereof.